The primary objectives of the proposed research are: 1. To determine the association between bacteremia with members of the family Bacteroidaceae and Thromboembolic Disease. 2. To determine the mechanisms by which cell wall components of gram-negative anaerobic microorganisms activate the coagulation system. 3. To characterize the humoral factors responsible for neutralizing the clot-promoting effects of lipopolysaccharide (LPS) and lipid A prepared from gram-negative anaerobic microorganisms. The methods to be used are: 1. Recalcified clotting time of platelet deficient plasma for determining the clot-promoting effects of cell wall components. 2. Chromatographic methods for isolation of Hageman factor (Factor XII), pre-kallikrein, IgM any IgG from normal human plasma or serum. 3. Folin method for quantitating protein in the purified preparations. 4. Double immunodiffusion for identifying LPS and lipid A. 5. Indirect hemagglutination and complement dependent hemolysis of sheep erythrocytes for determination of LPS and lipid A antibody titers.